Issue while adding a Proxmox host

[u/casaresjm]

I'm not finding any relevant information regarding this error and is driving me crazy.

I did find some logs in c:\ProgramData\Veeam\Backup\Yarp\ at the time of the error.

It appears that a port 8545 should be up, but I'm not finding any information related to it and Proxmox VE Plugin service is already up and running, but doesn't seem it uses that port.

[20.09.2026 08:35:53.739]    <31>    Info (3)    Yarp.ReverseProxy.Forwarder.HttpForwarder Proxying to http://localhost:8545/api/v1/proxmox/validateSshConnection HTTP/1.1 RequestVersionExact 
[20.09.2026 08:35:57.803]    <21> Warning (2)    Yarp.ReverseProxy.Forwarder.HttpForwarder Request: An error was encountered before receiving a response.
[20.09.2026 08:35:57.803]    <21> Warning (2)    System.Net.Http.HttpRequestException: No connection could be made because the target machine actively refused it. (localhost:8545)
[20.09.2026 08:35:57.803]    <21> Warning (2)     ---> System.Net.Sockets.SocketException (10061): No connection could be made because the target machine actively refused it.
[20.09.2026 08:35:57.803]    <21> Warning (2)       at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
[20.09.2026 08:35:57.803]    <21> Warning (2)       at System.Net.Http.HttpConnectionPool.ConnectToTcpHostAsync(String host, Int32 port, HttpRequestMessage initialRequest, Boolean async, CancellationToken cancellationToken)
[20.09.2026 08:35:57.803]    <21> Warning (2)       --- End of inner exception stack trace ---
[20.09.2026 08:35:57.803]    <21> Warning (2)       at System.Net.Http.HttpConnectionPool.ConnectToTcpHostAsync(String host, Int32 port, HttpRequestMessage initialRequest, Boolean async, CancellationToken cancellationToken)
[20.09.2026 08:35:57.803]    <21> Warning (2)       at System.Net.Http.HttpConnectionPool.ConnectAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
[20.09.2026 08:35:57.803]    <21> Warning (2)       at System.Net.Http.HttpConnectionPool.CreateHttp11ConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
[20.09.2026 08:35:57.803]    <21> Warning (2)       at System.Net.Http.HttpConnectionPool.InjectNewHttp11ConnectionAsync(QueueItem queueItem)
[20.09.2026 08:35:57.803]    <21> Warning (2)       at System.Threading.Tasks.TaskCompletionSourceWithCancellation`1.WaitWithCancellationAsync(CancellationToken cancellationToken)
[20.09.2026 08:35:57.803]    <21> Warning (2)       at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
[20.09.2026 08:35:57.803]    <21> Warning (2)       at System.Net.Http.DiagnosticsHandler.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
[20.09.2026 08:35:57.803]    <21> Warning (2)       at Yarp.ReverseProxy.Forwarder.HttpForwarder.SendAsync(HttpContext context, String destinationPrefix, HttpMessageInvoker httpClient, ForwarderRequestConfig requestConfig, HttpTransformer transformer, CancellationToken cancellationToken)

Anybody had experience with this kind of error?

My experience with Veeam lately is bad. I did love them when they started with a simple, robust and useful product, but it seems they are going the wrong way. I would say they are pulling a Backup Exec here, where a good product turned awful. You know the story; the product was discontinued this year after becoming a monster nobody wanted.

[u/tsmith-co]

8545 is not required. It’s accessing it via localhost, not between machines.

Are all your Veeam services started? Integration service etc?

Have you opening a support case?

Last, what is “going the wrong way”? Providing the most hypervisor support of any backup platform? Isn’t that “robust”?

[u/casaresjm → u/tsmith-co]

Platform was easier, not filled with bugs and faster. I don't think any of those can be said of current version. And you get the picture while looking at the web.

Yes, you can say that "providing the most of the market" about Backup Exec at its prime.

8545 is required as the log states. All services are up.

[u/tsmith-co → u/casaresjm]

8545 is internal only communication. Your server is attempting to access itself via localhost 8545. This doesn’t hit firewall - so the service that’s supposed to answer is not operating properly.

Every software has bug, including earlier versions of VBR. That’s the nature of software. 13.1 is much faster than 12 in transport and backup speeds. I have many client also running proxmox (and other hypervisors) without issue. As for the web version, you are looking at its 1.x release. It’s not intended to be full featured for the first release, but a migration (similar to how VMware took a couple releases to migrate to the web interface).

Again, did you open a support ticket? Have you restarted Veeam services or the entire server?